Tampons

ABSTRACT

A tampon for hygienic use which comprises an absorbent core of general cylindrical shape having a liquid pervious cover layer is disclosed. The cover layer is a plastics material which comprises parallel ribs in one direction interconnected by a plurality of fibrillated strands in the transverse direction. The ribs of the cover layer lie in a direction which is in a direction parallel to the main axis of the tampon.

The present invention relates to tampons for hygienic use and toprocesses for their preparation.

Conventional tampons for hygienic use normally comprise an absorbentcore containing hydrophilic material such as hydrophilic foam or fibreswhich has been formed into general cylindrical shape by for examplecompressing or moulding. Conventional tampons, however, have been foundto be relatively uncomfortable to insert into the vagina due to the "dryfeel" and abrasiveness of the absorbent fibre or foam surface of theabsorbent core of these tampons. Furthermore conventional tampons whichcomprise an absorbent core containing hydrophobic cellulose fibres suchas wood pulp fibres tend to shed these fibres when the absorbent corebecomes moist in use, and in particular during insertion or removal ofthe tampon from the vagina. It is known from the disclosure of EuropeanPatent No. 149155 and United Kingdom Patent NOs. 1218641 and 2010680that the absorbent core of tampons of this type can be provided with aliquid pervious non-woven fabric cover layer to inhibit in use sheddingof fibres from the absorbent core. It is further disclosed in theaforementioned European Patent No. 149155 that such a non-woven fabriccover layer can also render the tampon more comfortable to insert intothe vagina because the smoother nature of the non-woven fabric reducesthe surface drag or resistance of the tampon during insertion. It hasnow been found that similar advantages can be obtained using analternative cover layer material over the absorbent core of a tampon.

Accordingly the present invention provides a tampon for hygienic usewhich comprises an absorbent core of general cylindrical shape having aliquid pervious cover layer wherein the cover layer is a plasticsmaterial which comprises parallel ribs in one direction interconnectedby a plurality of fibrillated strands in the transverse direction andwherein the ribs of the cover layer lie in a direction parallel to themain axis of the tampon.

FIG. 1 is an isometric view of a tampon, in accordance with the presentinvention.

Suitable plastics materials for use in the invention include thoseplastics materials disclosed in United Kingdom Patent No. 1548865 thedisclosure of which is incorporated herein by cross reference. Theseplastics materials have thicker relatively smooth ribs interconnected bythinner fibrillated strands which provide the plastics materials with asmooth or soft feel in the direction of the ribs. A cover layer of suchplastics material will therefore advantageously provide the absorbentcore of a tampon of the invention with a smooth feel in the longitudinaldirection thereof thereby rendering the tampon more comfortable toinsert or withdraw from the vagina.

The plastics material has holes defined by the interconnected ribs andstrands of the material. The size of the holes will therefore depend ondensity of ribs and strands in the material.

The plastics material can suitably have 4 to 20 ribs/cm and canpreferably have 5 to 15 ribs/cm. Similarly the plastics material cansuitably have 8 to 50 fibrillated strands/cm and can preferably have 10to 40 fibrillated strands/cm.

It has been found that densities of ribs and fibrillated strands withinthe hereinabove ranges can provide a plastics material with holes whichare sufficiently small to inhibit penetration of the material by moistfibres. Such a plastics material when used as a cover layer over theabsorbent core of a tampon of the invention will thereforeadvantageously inhibit shedding of fibres from the absorbent core duringuse.

Suitably the plastics materials for use in the invention can have aweight per unit area of 2 to 30 g/m², desirably a weight per unit areaof 2 to 20 g/m² and can preferably have a weight per unit area of 4 to12 g/m².

Suitably plastics materials for use in the invention can have thicknessof 0.03 mm to 0.15 mm and preferably have a thickness of 0.04 mm to 0.10mm.

The plastics materials used in the invention will normally comprise apolymer which is relatively non-water absorbent to provide the tampon ofthe invention with a cover layer which similarly non-water absorbent.The polymer is preferably a thermoplastic polymer such as a polyolefine,polyamide or polystyrene to render the plastics material advantageouslyheat sealable.

The plastics materials used in the invention preferably a blend ofincompatible polymers. Suitable blends comprise a major proportion of apolyolefine such as polypropylene, high density polyethylene orethylene--propylene copolymers and a minor proportion of an incompatiblepolymer such as polystyrene, for example high impact polystyrene orpolyamide.

An "incompatible polymer" is a polymer which in a blend therewith is notmiscible with the polyolefine polymer. In such a blend the polymerswould form separate phases and the polymer in the lower concentration(normally the incompatible polymer) would form a discrete disperse phaseand the polymer present in the higher concentration (normally thepolyolefine polymer) would form a continous phase.

Favoured plastics materials for use in the invention comprise a blend ofhigh density polyethylene with 5 to 20% by weight of high impactpolystyrene.

Apt plastics materials for use in the invention which comprise a blendof high density polyethylene with 8 to 10% by weight of high impactpolystyrene, have a weight per unit area of 5 to 11 g/m² and a thickness0.40 to 0.120 mm are known as net 909 (Trade mark) grades A4, A7, 48Cand DHM available from Smith and Nephew Plastics Ltd.

The plastics material can advantageously be a composite material whichcomprises a substrate layer of higher melting point polymer and a heatsealable layer of a lower melting point polymer. Suitable plasticsmaterial of this type are given in United Kingdom Patent No. 2142246.

The absorbent core of the tampon of the invention will normally comprisea hydrophilic material such as hydrophilic fibres or hydrophilic foam.Suitable hydrophilic fibres include conventional hydrophilic cellulosicfibres such as wood pulp viscose or cotton fibres. A minor amount ofhydrophobic fibres however may be present in the absorbent core.

The absorbent core of the tampon will preferably comprise compressedhydrophilic fibres to render the tampon expandible during use. Favouredtampons of this type expand in a lateral direction in use. Preferredlateral expanding tampons comprise a radially compressed spirally woundstrip of hydrophilic fibres. Tampons of this type are disclosed inaforementioned European Patent No. 149155.

The cover layer of plastics material can cover the whole of the surfaceof the absorbent core of tampon. It is preferred however that the coverlayer of plastics material covers only the side surface of the absorbentcore.

The cover layer of plastics material can advantageously be attached tothe surface of the absorbent core to inhibit displacement of the layerduring insertion or withdrawal of the tampon. The cover layer can beattached to the surface of the absorbent core by means of a conventionalbonding method such as adhesive bonding or preferably heat bonding. Theplastics materials for example in the form of a strip may heat bonded tothe surface of the absorbent core over the whole or preferably over apart of its area or length. The bonded area may be continuous ordiscontinuous portion for example in the form of strips or dots.

The tampon of the invention can optionally be provided with a roundedinsertion end to facilitate insertion of the tampon into the vagina.

The tampon can be packaged in a conventional over wrap for use as adigital tampon or within an applicator package for insertion by means ofan applicator.

In another aspect the present invention provides a process for forming atampon of the invention which comprises spirally winding a strip ofabsorbent material which is attached at an end portion thereof to astrip of liquid pervious material and radially compressing the woundstrip to form a tampon which comprises an absorbent core of generalcylindrical shape having a cover layer of the liquid pervious materialwherein the liquid pervious material is a plastics material whichcomprises parallel ribs in one direction interconnected by a pluralityof fibrillated strands in the transverse direction and the ribs of theplastics material lie in the longitudinal direction of the tampon.

The strip of absorbent material will normally have a width similar tothat of the length of the formed tampon. The strip of liquid perviousmaterial may be wider than the strip of absorbent material to ensurethat the liquid pervious material covers one or both ends of the woundstrip.

It is preferred however that the width of the strip in the same or lessthan the width of the strip of absorbent material to ensure that theliquid pervious material covers only the side surface of the woundstrip.

The parallel ribs in the strip of liquid pervious material will normallylie in the transverse direction of the strip to ensure that the parallelribs of the liquid pervious material cover layer on the tampon lies inthe longitudinal direction of the tampon.

The strip of liquid pervious material can be attached to the strap Ofabsorbent material by any convenient bonding method such as adhesive orheat bonding. It is preferred that a heat bonding method is used.Suitable bonding methods include those given aforementioned EuropeanPatent No. 149155.

The strip of liquid pervious material will be attached to end portion ofthe strip of absorbent material. The end portion will have a lengthwhich is at least 10% desirably at least 30% and preferably at least 75%for example 90% of the length of liquid pervious material.

The combined strip can be spirally wound by a conventional method suchas the methods disclosed in European Patent No 149155 and United KingdomPatent NO. 1392995.

The strip of liquid pervious material will have a length which issufficient to cover the wound strip and preferably length which issufficient to overlap the attached portion thereof.

The unattached end portion of the wound strip of liquid perviousmaterial which overlaps the attached portion thereof and can be thenbonded to the back of this portion by a suitable method for example heatbonding to secure the wound strip. The wound strip can be radiallycompressed by a conventional method such as the methods disclosed inEuropean Patent No. 149155 and United Kingdom No. 1082440 to form atampon of the invention.

The tampon may be provided with a rounded end by conventional methodsuch as the method disclosed in United Kingdom No. 1046066.

With respect to the drawing, FIG. 1 shows a tampon 1 having an absorbentcore of generally cylindrical shape. The core 2 has a longitudinallyextending main axis A. Surrounding core 2 is a liquid pervious cover 3having ribs 4 that lie in a direction parallel to the main axis A andthat are interconnected by fibrillated strands 5 that lie in a directiontransverse to the main axis A. As shown, the cover layer 3 covers onlythe cylindrical surface of the core 2 and lies between the end portions6, 7. A cord is secured to end portion 7.

EXAMPLE

A strip of liquid pervious plastics material (length 110 mm width 48 mm)was attached at a overlap end portion (length 30 mm) by heat sealing theone end of a strip (with 52 mm length 250 mm) of viscose fibres and thecombined strip spirally wound to form an absorbent core of generalcylindrical shape having a cover layer of the plastics material over itsside surface. The non-attached end portion (length 16 mm) of theplastics material was then heat sealed over the attached end portion tohold the cover layer in place. The core and cover layer was thenradially compressed to form a tampon of the invention (diameter 14-17mm).

The plastics material used in this Example (known as net 909 ref H80)had 11/cm longitudinal parallel straight ribs interconnected byapproximately 15/cm fibrillated strands and had a weight per unit areaof 9 g/m². The ribs of the plastics material were in the longitudinaldirection of the tampon. The strip was spirally wound by the methodgiven in United Kingdom Patent No. 1392995 and the wound strip radiallycompressed by the method given in United Kingdom No. 1082770.

In a subjective test, it was found that tampons of the invention weresignificantly better with respect to ease of insertion and withdrawal atboth the beginning and end of menstruation than tampons of similarconstruction but not provided with a cover layer.

We claim:
 1. A tampon for hygienic use which comprises an absorbent coreof general cylindrical shape having a main axis, said absorbent corehaving a liquid pervious cover layer wherein the cover layer is aplastics material having ribs which lie in a direction parallel to themain axis of the core and are interconnected by a plurality offibrillated strands in a direction transverse to the main axis of thecore.
 2. A tampon as claimed in claim 1 in which the plastics materialcomprises a polyolefin.
 3. A tampon as claimed in claim 2 in which theplastics material is a blend which comprises a major proportion ofpolyolefin and a minor proportion of an incompatible polymer.
 4. Atampon as claimed in claim 3 in which the plastics material is a blendof high density polyethylene and polystyrene.
 5. A tampon as claimed inclaim 4 in which the blend contains 5 to 20% by weight of high impactpolystyrene.
 6. A tampon as claimed in claim 1 in which the plasticsmaterial has 5 to 15 ribs/cm and 10 to 40 fibrillated strands/cm. .
 7. Atampon as claimed in claim 1 in which the plastics material has a weightper unit area of 2 to 20 g/m².
 8. A tampon as claimed in claim 1 inwhich the plastics material is a composite material comprising asubstrate layer of higher melting point polymer and a heat sealablelayer of lower melting point polymer.
 9. A tampon as claimed in claim 1having two end portions with said absorbent core being between said endportions, and a cylindrical surface in which the cover layer of plasticsmaterial covers only the cylindrical surface of the absorbent core ofthe tampon.
 10. A tampon as claimed in claim 1 in which the absorbentcore comprises a radially compressed spirally wound strip of hydrophilicfibres.
 11. A tampon as claimed in claim 1 in which the cover layer is astrip of ribbed plastics material attached to the cylindrical surface ofthe absorbent core of the tampon.
 12. A process for forming a tampon asclaimed in claim 1 which comprises spirally winding a strip of absorbentmaterial which is attached at an end portion thereof to a strip ofliquid pervious material having a width and a length and radiallycompressing the wound strip to form a tampon which comprises a core ofgeneral cylindrical shape having a cover layer of the liquid perviousmaterial wherein the liquid pervious material is a plastics materialwhich comprises parallel ribs in one direction interconnected by aplurality of fibrillated strands in the transverse direction and theribs of the plastics material lie in a direction parallel to the mainaxis of the tampon.
 13. A process as claimed in claim 12 in which thestrip of liquid pervious material is the same or less than the width ofthe strip of absorbent material to ensure that the liquid perviousmaterial covers only the surface of the wound strip of absorbentmaterial between the ends thereof.
 14. A process as claimed in claim 12in which the end portion attached to the strip of absorbent material hasa length which is at least 30% of the length of the strip of liquidpervious material.
 15. A process as claimed in claim 12 in which thestrip of liquid pervious material is attached to the end portion of thestrip of absorbent material by heat bonding.
 16. A process as claimed inclaim 12 in which the wound strip of liquid pervious material has anattached end overlapping the attached end portion thereof and isattached thereto by heat bonding.